Technical Field
The present invention relates to a method of measuring the location of a user. More particularly, the present invention relates to a distance measuring method by comparing vision sensor images to database. Using this method, a distance measuring is possible without GPS, and it is possible to deduct depth values of target objects by a comparison of 2D side-section images to database information.
Background
The conventional methods of measuring the location of a user are a method for measuring location by using GPS (Global Positioning System) and a method for measuring the location of a user by applying triangulation based on mobile communication signals.
However, these conventional methods have numerous problems. In case of GPS, although it performs measuring of location outside with high accuracy, it does not work in particular environments such as indoors, the basement, and the downtown where GPS signals are blocked. And the measuring method based on mobile communication signals and triangulation is less accurate than GPS in measuring location and tends to be influenced by the surrounding environments of a user. Besides these methods, other distance measuring methods based on various forms of technology such as Wi-Fi and RFID have been suggested.
Meanwhile, with the recent development of optical technology, various distance measuring methods using vision sensor have been suggested. Representatively, in the case of stereo vision using binocular method, it measures distance to the target object by comparing images acquired through vision sensor. Another method for distance measuring is to measure distance to the target object by comparing the ratio of a particular object on side-section image acquired through single vision sensor and to provide a user with it. This method enables the development of various applications. In addition, there is an apparatus for expressing images in distance information by combining a ultra-red sensor and a vision sensor.
Each technology has advantages and disadvantages. The stereo vision using binocular method uses the method of reading images by two vision sensors and the distance measuring method by combining two images. As the stereo vision represents the distance difference by different angle of views of image information, it has a high accuracy in terms of positioning that represents relative distance. However, as the stereo vision represents only limited range of distances and it deals with two images at the same time, it has a difficulty in managing in real time due to high computational complexity.
The distance measuring method that measures the distance to the target object by comparing the ratio of a particular object on side-section image is successful in fixed and structured environments such as a standardized space, but the method may not be used in environments that are not standardized and structured since a successful result may not be expected in such environments.
The distance measuring method that acquires images and distance information at the same time by combining a ultra-red sensor and a vision sensor has less computational complexity compared to the stereo vision using binocular method and has an advantage of generating a successful result in the environments full of changes compared to the distance measuring method by comparing the ratio of a particular object on side-section image. However, it has a disadvantage in that it may be only used in restricted spaces in terms of distance as the reliability and accuracy of the distance information measured by infrared rays are drastically reduced when the distance to objects exceeds a regular scope.